Astronomers have observed a massive star in the nearby Andromeda galaxy that appears to have disappeared without exploding, potentially forming a black hole in a failed supernova. Recent telescope observations reveal a faint remnant shrouded in dust, though alternative explanations like a stellar merger remain possible. This rare event highlights new insights into the fates of massive stars.
In the Andromeda galaxy, a star known as M31-2014-DS1, roughly 20 times the mass of the sun, underwent a dramatic change at the end of its life. First noted for brightening in 2014, it faded significantly between 2017 and 2020, prompting researchers to investigate.
Kishalay De at Columbia University in New York and his team initially suspected a failed supernova in 2024, where the star collapses directly into a black hole without the typical explosion. However, early observations showed no accompanying X-ray emissions, a common sign of black hole formation.
Using the James Webb Space Telescope (JWST) and Chandra X-ray Observatory, the team recently detected a faint, red object at the star's location. This remnant is only about 8 percent as bright as the original star and is enveloped in a rapidly expanding cocoon of dust, consistent with models of a failed supernova.
Yet, a separate analysis of the same JWST data by Emma Beasor at Liverpool John Moores University in the UK suggests ambiguity. "The predictions for what a failed supernova looks like overlap quite significantly with what we might expect from two stars colliding and producing loads of dust," Beasor notes. She adds that such significant fading in stars is uncommon, regardless of the cause.
Gerard Gilmore at the University of Cambridge emphasizes the excitement of the discovery. "In either explanation, this is exciting. The visible star really has gone away," he says. While no X-ray radiation has been detected to confirm a black hole, advanced telescopes like JWST are enabling detailed study of these events. Gilmore describes it as "an amusingly Cheshire cat way to go" for massive stars, marking progress in understanding their endpoints.
The findings, detailed in preprints on arXiv (DOIs: 10.48550/arXiv.2601.0577 and 10.48550/arXiv.2601.05317), await peer review.